The invention relates to a packaging with foodstuffs and/or articles of daily use that are sterilized or disinfected for hygienic reasons. The invention also relates to a method for the sterilization, disinfection or partial disinfection of packaged goods.
As long as anyone can remember, sunlight has been credited with the power to counteract diseases or the spreading of infections. Later research showed that the bactericidal effect emanates from the invisible portion of the solar radiation below 320 nm. Therefore, already at the end of the 19th century, the first artificial UV radiation sources were developed and used. An effective disinfection method without chemical agents or the use of high temperatures was hence available.
In the process of the gentle production of foodstuffs and medicinal products, efficient packaging becomes more and more important. Because of changed products and consumer behavior, partially disinfected or aseptic packaging are filled with increasing frequency in order to optimally preserve the quality, prevent premature spoilage and the multiplication of disease-producing germs and hence overall extend the storage life. For the partial disinfection of packaging materials in particular, UV irradiation is a method that is used in practice. However, in many cases it is not sufficient to use disinfected packaging material since the products themselves are frequently contaminated by viruses and bacteria. For a hygienically acceptable packaging unit, the sterilization of the products is therefore necessary in addition. Nevertheless, the possibility that re-germination has occurred by the time the filling or actual packaging of the products takes place cannot be excluded. In any case, several process steps are necessary and high demands on hygiene and cleanliness have to be met when packaging and filling in order to produce a packaging unit that is as hygienically acceptable as possible.
For example, UV treatment of the wash and transport water with the help of which the foodstuffs are pre-purified takes place first. Subsequently, an additional UV treatment of the product to be packaged is required. For this, the different foodstuffs or goods pass through a section in which they are subjected to the UV radiation for a certain period of time in order to achieve a certain disinfection rate. The goal is to kill 90% of the germs residing on the surface and subsequently package the product under sterile conditions.
UV irradiation to disinfect products becomes more and more important since this method has many advantages compared to sterilization methods with peroxides or superheated steam. The methods are easy to apply, the properties of the product are not affected and the disinfection is very effective. During treatment, residues, corrosive or harmful substances are not formed, the smell and taste of the foodstuffs is not altered and the purchase and maintenance costs of the systems are low.
UVC rays have a shorter wavelength and are more energy-rich than UVA and UVB rays. They comprise the largest portion of the entire UV range and exhibit a strong germ-killing (bactericidal) effect. Just like the visible wavelengths of light, UVC rays only travel in a straight line and their intensity decreases with increasing distance from the source. As a matter of principle, UVC rays do not penetrate any material, including window glass.
UVC radiation is technically produced by mercury lamps, the primary radiation of which of 254 nm is very close to the maximum of the bactericidal action. Low-pressure lamps, high-pressure lamps or medium-pressure lamps are optionally used. The efficiency of low-pressure tubes with an efficiency factor of more than 90% in the bactericidal wavelength range is unsurpassed to this day. The remaining radiation of a low-pressure tube is distributed over secondary emissions such as light (above 400 nm) and heat.
The germicidal action of UVC rays is based on the following effects. The short-wave and energy-rich UVC rays are absorbed in certain sections of the genetic material (DNA). As a result, photochemical changes occur in certain sections of the helix, for example linkage reactions of adjacent functional groups. These sections become useless for the copying process of the helix strand operating by the template principle. The necessary passing-on of information does not happen. The cell can no longer multiply.
If the number of disruptions exceeds a level specific to each species, the cell dies without multiplying. As a consequence of this principle of action, germs are not killed in the proper sense! They are, in fact, inactivated and hence are prevented from building up a critical potential by cell division.